Figure 1.

Representative photomicrograph of a crypt-villus unit from a preterm lamb ileum (A) stained with hematoxylin and eosin. Crypt depth (lower-left line) was measured from the base of the crypt to the level of the crypt-villus junction, following any curves in the crypt lumen. Villus height (upper-right line) was measured from the crypt-villus junction to the tip of the villus. (B) Representative photomicrograph of the muscularis externa (capped black line) from a preterm lamb ileum, stained with hematoxylin and eosin. The inner circular (white line) and outer longitudinal (blue line) smooth muscle layers of the muscularis externa are situated on either side of the myenteric plexus of Auerbach. Scale bars = 20 µm.